Seals nap while diving down as deep as 300 meters, one study found. Jellyfish sleep, too, even though they have no brains; ...

Jellyfish do not have control over where they ... I got a shock of a sting across my lower cheek and I couldn't really sleep as it felt like it was on fire for two or three nights." ...

Jellyfish are known for drifting to and fro at the whim of ocean currents—but not all species are so passive. The millions of golden jellyfish that pack Palau’s Jellyfish Lake spend much of ...